Compact, highly mobile and efficient thermodynamic and energy systems are becoming increasingly important for a wide range of applications, such as for powering portable electronic, communication and medical devices, as well as for controlling sensor systems.
Historically, batteries, such as primary and rechargeable batteries, have been utilized for supplying portable, compact sources of power. However, portable batteries are generally limited to power production in the range of milliwatt to watts, and thus cannot address the need for significant power production. Further, they also cannot address the need for a mobile and lightweight power generating device. The environmental incompatibility of typical conventional batteries also poses a limitation for many applications.
U.S. Pat. No. 6,392,313 discloses a microturbomachinery that enables production of significant power and efficient operation of thermodynamic systems in the millimeter and micron range, as shown in FIG. 1.
Referring to FIG. 1, in operation, air 12 enters the micro-gas turbine engine 10 (hereinafter also referred to as the microengine) axially along the centerline 14 of an inlet 16 and turns radially outward. It is then compressed in a centrifugal, planar microcompressor. The microcompressor includes a compressor rotor disk 18, which has radial-flow rotor blades 20.
The compressor rotor disk 18 is connected to a shaft 40 that is radially journalled for spinning, whereby the compressor rotor disk 18 and blades 20 supported by the shaft 40 are spun. Stationary diffuser vanes 22 are located just beyond the radial periphery of the compressor rotor. As such, the air passing through the compressor rotor blades 20 can exit the rotor via the vanes 22 in the diffuser.
Fuel is injected at the discharge of the compressor rotor 18 by way of a fuel injector 24. The injected fuel mixes with the air while flowing radially outward. Combustion igniters 33 initiate combustion of the air-fuel mixture. The ignited mixture axially enters an annular microcombustion chamber 30 where the mixture is fully combusted.
Combustion exhaust gas from the microcombustion chamber 30 is discharged radially inward through stationary turbine guide vanes 34 to a planar radial inflow microturbine rotor formed of a rotor disk 36. The turbine disk 36 is connected by way of the journalled shaft 40 to the compressor disk 18 and thus rotationally drives the microcompressor in response to the combustion gas exhausted through microturbine blades 38, which causes the turbine disk 36 to spin.
The shaft 40 between the microcompressor and microturbine is preferably hollow and is supported upon air static bearings. The bearings are supplied by an air bleed 42 from the microcompressor exit. Correspondingly, the shaft bearing discharges the air through the holes 44 in the microturbine.
Under a high temperature environment, it is very difficult to convert the rotating energy into the electrical energy. However, the aforesaid prior art microturbomachinery is not properly configured for power production by using the rotating energy of the shaft since it is not equipped with a cooling device.
Also, since the air static bearing is used for supporting the rotating shaft, the prior art microturbomachinery is disadvantageous in that the performance of the bearing is considerably influenced by the manufacturing tolerance. Thus, the manufacturing process of the overall system must be maintained very strictly and may become complicated. It also causes an increase in manufacturing costs. Such a shortcoming means that there is a great difficulty in achieving the operational stability of the system.